With just eight days left until the NDP leadership convention, Nathan Cullen says he's optimistic about the outcome.The Skeena-Bulkley Valley MP is one of seven candidates to become the party's next leader and has been campaigning for the position since September. Because of the NDP's success in the last federal election, whoever wins next weekend's leadership will also become the leader of Canada's official opposition."Our campaign has been doing very well," Mr. Cullen said Friday morning from Vancouver. "We're feeling quite good, but we're still an underdog, we appreciate that."According to financial information filed by the candidates, Mr. Cullen attracted the most donors of any candidate in the first half of February, and raised almost as much money as front-runner Thomas Mulcair. Most of Mr. Cullen's support is coming from British Columbia.During the coming week, as he prepares for the convention in Toronto, he said his biggest challenge will be staying focused and not getting ahead of himself. He said a campaign is like a marathon, and he intends to enter the final stretch of the race at full-out speed."We won't stop til we're past the finish line," he said. "Hang onto to your hats kids, this is going to be fun."